Watts and kv are seperate measures of performance. Watts say how much power the motor can safely consume (if it's doing it effeicently, then how much power it can put into the air), and kV is how quickly the motor will like to spin (measured unloaded, but it'll drop dramatically as you over-prop the motor).
Getting similar wattage, when propped right won't have a huge affect (not much difference between 230, 250 and 280W, but huge diffrence between 85, 160, and 300W). keep in mind, this is a max rating. Put on a smaller prop, or lower voltage battery and you'll never hit these power levels. too big on either, and low throttle might be fine, but WOT will overheat and burn out the motor eventually.
KV is a complex beast -- it sets how fast the motor spins, but you can change the pitch of the selected prop to adjust the final speed up and down. No harm in picking the same (or nearly the same KV) but moving a few hundred each way will start to affect your prop selection and top speed, several hiundred will have a strong affect.
As for the ESC, look at the max current . . . oh wait, some of these don't publish that. If they do, I usually make sure the ESC is at least 10% above that. if they don't, but publish the wattage, a conservitive measure would be:
W/(cells*4v)
So for a 250W motor that can handle a 3S or 4S pack:
250W/(4S*4v) = 15.6 -> add 10%, so it needs ~18A ESC
Keep in mind, the watt rating is always made on the highest cell count the motor is designed to handle. picking a lower one you use result in much higeher currents, and an oversized ESC estimate.